Question from Reddit user:
I’m trying to track app install attribution for iOS using Google Analytics + Firebase — specifically to attribute installs back to the original traffic source (e.g., Google Ads, Meta, or other ad networks, owned web site, sns).
However, after reviewing both Firebase and GA documentation, I haven’t found a clear or official way to achieve this. Unlike Android, iOS doesn’t support install referrer tracking, so it’s technically difficult to understand which ad or traffic source led to an install when the user flows through the App Store.
From what I understand, this attribution gap stems from iOS limitations, particularly:
- No access to install referrer (like on Android)
- SKAdNetwork data in Firebase is available only for Google Ads
- UTM parameters aren’t preserved through App Store redirect
Given these constraints, I’m considering proposing a Mobile Measurement Partner (MMP) solution internally — like AppsFlyer — since MMPs seem to have:
- Probabilistic modeling
- Integration with non-Google ad networks
- Device ID matching (where allowed)
- Broad SKAdNetwork support
But I’m struggling to make the case without solid confirmation that GA + Firebase alone can’t deliver reliable iOS install attribution across multiple ad platforms.
If anyone has implemented this (or tried), I’d love to hear:
- Can GA + Firebase truly support iOS install attribution outside of Google Ads?
- Or is an MMP the only viable path for reliable, cross-channel iOS attribution?
Thanks in advance!
Answer from Nabil:
The short answer is:
No, Google Analytics 4 (GA4) with Firebase alone cannot provide reliable, cross-channel iOS app install attribution outside of Google Ads, and you absolutely should proceed with proposing a Mobile Measurement Partner (MMP) solution like AppsFlyer.
The constraints you identified, especially the lack of an install referrer on iOS and the limited scope of Firebase’s SKAdNetwork integration, create an insurmountable attribution gap for traffic from Meta, other paid networks, and even your owned channels.
An MMP is the only viable path for reliable, comprehensive iOS attribution because they are specifically designed to bridge these gaps using proprietary methodologies like probabilistic modeling and broad API integrations with ad networks that go far beyond what GA4 and Firebase offer natively.
The long answer is:
Your understanding of the iOS attribution challenge is perfectly accurate, and you have hit the ceiling of what the GA4 and Firebase ecosystem can provide on its own for cross-platform iOS measurement.
The core problem is that GA4 and Firebase are limited to two methods: deterministic matching (which is blocked by the App Store redirect) and Google’s internal systems.
While Firebase automatically reports conversions from Google Ads by leveraging the Google Click ID ($$gclid$$) and its deep integration with the App Store and SKAdNetwork, it has no native mechanism to perform the necessary link matching for other networks like Meta, TikTok, or even for your custom organic sources.
This is precisely why a dedicated MMP is a necessity.
The excellent solution involves creating a unified data layer by implementing the Firebase SDK for your core app events, while simultaneously integrating an MMP like AppsFlyer.
This two-pronged approach ensures that you get the best of both worlds.
The MMP leverages the LinkedIn Conversions API (or other network APIs) and its own proprietary probabilistic and impression-based modeling to determine the likely source of every install, matching pre-click data from the ad networks with post-install data from the device and your in-app events.
Meanwhile, your Google Analytics for Firebase implementation will continue to collect your high-quality in-app event data, such as purchase or level_start.
The critical step then is to use the MMP’s platform to send the finalized, attributed install and conversion data back to both GA4 and your ad platforms.
The MMP can pipe this reliable, attributed data into GA4 via a server-side integration, allowing your GA4 reports to finally show accurate attribution for Meta and other channels, not just Google Ads.
Furthermore, the MMP can use the Google Ads API and the Meta Conversions API to send attributed conversion events directly back to the respective ad platforms.
This closed-loop system is essential for optimizing your campaigns, as it ensures that the ad networks receive accurate, reliable conversion signals that they can use to improve their bidding algorithms, which is something GA4 cannot facilitate for non-Google ad platforms.
In short, an MMP isn’t just nice to have; it is the industry standard tool for achieving the cross-channel iOS attribution you require.
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